AbstractHexene‐doping graphitic nanoplatelets (HxGNs), as a new filler, have extraordinary properties (e.g., hexene‐functionalization, wedge‐shaped pore, high specific surface areas, and so on), and interfacial interactions with hydrophobic polymers. Thus, the HxGNs sufficiently increase the mechanical properties of poly(vinyl chloride) (PVC). HxGN@PVC_X nanocomposites can be prepared easily with a solution casting method because the HxGNs are well dispersed in tetrahydrofuran. The tensile strength, Young's modulus, toughness, and strain‐to‐failure of HxGN@PVC_5 nanocomposites increase by approximately 33.1%, 27.3%, 58.6%, and 40.5%, respectively, compared with pure PVC. Especially, the low toughness of PVC, which hinders practical applications, has been greatly improved. The improved performance is from the outstanding properties of the HxGNs and the excellent interfacial interactions between the HxGNs and PVC chain. As a result, HxGNs as a filler act as a reinforcing agent and plasticizer for the PVC matrix.Highlights The performance of the HxGN@PVC_5 nanocomposites is increased. The HxGN into PVC matrix is effective to overcome the disadvantages of PVC. A mechanochemical reaction can make graphitic nanoplatelets with specific groups. Graphitic nanoplatelets with specific groups can be used as new filler.